Mesozoic Geology

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					  Mesozoic Geology

Beginning of the Modern World
                                       Geologic Time Scale
                 Eon              Era                 Period              Age (Myrs) Epoch
                                                                                     Holocene
                                                                             0.01



Mesozoic
                                                     Quaternary
                                   C                                                Pleistocene
                                                                             1.8
                                   e
                                                                                     Pliocene
                                   n                                         5.3
                                                               Neogene
                                   o
                                                                                     Miocene
                                   z                                         23.8
                                   o
                                               Tertiary                             Oligocene
                                   i                                         33.6
                                   c                          Paleocene               Eocene
                                                                             54.8


248-65 Myr        P
                  h
                                   M
                                                                             65
                                                                                    Paleocene

                  a                                  Cretaceous
                                   e
                  n                                                          144
                                   s
                  e
                                   o
                  r                                   Jurassic
                                   z
                  o                                                          206
                                   o
                  z
                                   i                   Triassic
                  o
                                   c                                         248
                  i
                  c                                   Permian
                                                                             290
                                   P               Pennsylvanian
                                   a                                         323
                                   l                Mississippian
                                                                             354
                                   e
                                   o                  Devonian
                                                                             417
                                   z
                                   o                   Silurian
                                                                             443
                                   i
                                   c                 Ordivician
                                                                             490

                                                      Cambrian
                                                                             543
             P
             r   Proterozoic
             e
                                                                             2500
             c
             a
             m   Archean
             b
                                                                             3800
             r
             i
             a   Hadean
             n
                 Age of the Earth 4600 Myrs (4.6 Byrs)
                       Source: Geological Society of America (1999)
Highlights of Mesozoic Geology
1. Pangea was breaking up to form the
   “modern continents”
2. East Coast of NA rifted to become a
   passive margin, while the West Coast
   became active
3. Sea level went from a Phanerozoic low in
   the Triassic to a Phanerozoic high in the
   Cretaceaous
4. Dominated by warm climate (no ice ages)
           Mostly Oceanic
           Deposits




 Mostly
Orogenic
 Rocks          Mostly
                 Rift
                Rocks



Mesozoic
 Rock
     The Breakup of Pangea
1. Rifting of Laurasia and Gondwana to
   expand the Tethys Sea
2. Rifting of Gondwana to form Indian Ocean
3. Rifting of South America & Africa
   forming southern Atlantic
4. Rifting of North America and Europe to
   form North Atlantic
5. Rifting of Australia & Antarctica
Beginning of the Triassic
Late Triassic
    Jurassic
1
Early Cretaceous




                   2
    Middle Cretaceous
3                       4
Late Cretaceous




                  5
East Coast Geology
    Jurassic
1
Rifting
Margin
   East
 African
Rift Valley


Volcanic Rocks
Lake & River Sediments
Evaporites
Marine Deposits
Palisades Sill (Basalt), NY
Evaporites in the Gulf
Mesozoic Oil
 Deposits
Rifting
Margin
What’s Happening in the West?
Orogenies
  Active
 Margin:
Subduction
Mesozoic
Batholiths
 West
“Coast”
 Terrane
Accretion
  & the
Growth of
  North
America
Andean Orogeny
Central US Geology
High             Mesozoic
                  Seas
       Low




             Transgression   Regression
Sedimentary Sequences of NA




            Blue = No deposition
Cretaceous
 Seaway
  Mesozoic Climate - Hot Times

Triassic: Arid and Warm


                Cretaceous: Warm and Wet
        Evidence -
     Triassic/Jurassic
                         Fossils
                         Dunes




Redbeds




          Evaporites
         Evidence - Cretaceous




Arctic Dinosaurs

                   Arctic Coal
      What Led to Cretaceous
            Climate?

1. High Sea Level - Absorbs more solar
   energy
2. Increased Carbon Dioxide - Greenhouse
   Effect
    Increased Sea Floor Spreading
    Superplumes?
        Superplumes &
Large Igneous Provinces (LIPS)




  Several Oceanic Plateaus formed around 125 Myrs
Warm Oceans and Oil
Mesozoic Extinctions
            Mesozoic Extinctions

When           Species     Major Loses to
(End of…)      Loss**
Triassic       80 ± 4%     Most synapsids

Cretaceous     76 ± 5%     Dinosaurs, marine reptiles,
                           ammonites


   Triassic Extinction led to Dominance of Dinosaurs
   K/T
Extinction
Evidence




                Shocked Quartz




      Iridium
Global Distribution of Iridium
The Impact Site
    What
  Happened?

Immediate Area
1. Tsunami & Fallout
    What Happened?
Global Effects
1. Darkness - decrease in photosynthesis
2. Cold (2-3 Months of -20°C)
3. Followed by Greenhouse warming
4. Acid Rain
5. Wildfires
6. Toxic Seawater

				
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